Bonding agents have been developed for coating the surface of ammonium perchlorate particles. Bonding agents for broad and specific uses have been developed to achieve certain end results. One example of a bonding agent and its benefit is MT4 (reaction product of 2.0 moles of tris-1-(2-methylaziridinyl)phosphine oxide, 0.7 mole adipic acid, and 0.3 mole tartaric acid), HX752 (bis-isophthaloyl-1-(2-methylaziridine), and BIDE (butyliminodiethanol) in combinations of 0.10% to 0.20%, 0.10% to 0.12%, and 0.02% to 0.05% weight percent range respectively of a hydroxy-terminated polybutadiene propellant composition to achieve improved propellant aging and low temperature physical properties. Other bonding agents such as BA114, the reaction product of equimolar quantities of 12-hydroxystearic acid and tris[1-(2-methylazirdinyl)]phosphine oxide, have also imparted very desirable mechanical properties to composite propellants.
Other types of compounds including certain amine compounds such as TEPAN, partially cyanoethylated tetraethylene pentamine, have long been used in the propellant industry as bonding agents in composite propellants containing ammonium perchlorate (AP). They greatly improve the mechanical properties of such propellants by chemically bonding AP particles to the binder matrix. TEPAN is also known to facilitate processing relative to other bonding agents since the mix viscosity of the propellant is not increased as much by TEPAN as it is by most other bonding agents.
The glycidol reaction product of cyanoethyl-substituted tetraethylenepentamine or Tepanol has been employed as a bonding agent for polyurethane propellants containing ammonium perchlorate as the oxidizing agent.
Adducts of TEPAN and TEPANOL are disclosed in U.S. Pat. No. 4,493,741 along with their preparation as polyamine salt adduct bonding agents which produce equal or superior physical properties in HTPB composite propellants as compared to the parent compounds. These polyamine salt adduct bonding agents are prepared by adding a distilled water solution of the selected salt, e.g., ammonium sulfate (AS), ammonium formate (AF) or ammonium perchlorate (AP), to TEPAN or TEPANOL with stirring and heating, and subsequent evaporation of the volatiles. The polyamine salt adduct bonding agents are recovered as products having from about 25 to about 36 percent of the reactive amine groups of TEPAN or TEPANOL reacted with the ammonium ion of the ammonium salt selected.
U.S. Pat. No. 4,531,989 employs the polyamine salt adduct bonding agents of U.S. Pat. No. 4,493,741 in a polyester binder propellant composition wherein because of its insolubility in the polyester binder it is effective in improving mechanical properties. Unlike hydroxy-terminated polybutadiene wherein a bonding agent is solubilized and still can function as a bonding agent for inorganic ammonium oxidizer salts in the propellant matrix, polyester binders that solubilize the bonding agent renders the bonding agent ineffectual as a bonding agent.
The mechanism for polyamine salt adduct bonding agent in polyester binder requires the bonding agent to be finely dispersed since it is driven to the inorganic oxidizer salt surfaces where it homopolymerizes around or reacts with a second reactant, usually the propellant curative to form a shell which will subsequently react with the binder thus chemically reinforcing the binder/inorganic oxidizer salt matrix.
Although bonding agents have been found to be effective for certain binder systems, the use of other ingredients can render the bonding agent ineffective. A case in point is the preferred bonding agent, Tepanol, which is in near-general use within the propulsion community. Tepanol has been determined to be ineffective when used in a 2,2-bis(ethylferrocenyl)propane(Catocene)-catalyzed, high-burning rate composite propellants. Tepanol's ineffectiveness is evident from the results observed when it is used in a catocene-catalyzed, high-burning rate composite propellant composition wherein it fails to function as a propellant processing aid, and the propellant mix becomes very dry, stiff and lumpy with inadequate flow to be acceptably processible.
Therefore, an object of this invention is to provide a modification to the glycidol adduct of a partially cyanoethylated tetraethylenepentamine (Tepanol) wherein the "dry stage" in propellant processing which results from the hydrogen bonding of the Tepanol-coated ammonium perchlorate surfaces and the dewetting of the nonpolar prepolymer chain is prevented from taking place.
A further object of this invention is to provide a processing reagent which not only improves propellant processing of Catocene but functions in the propellant composition wherein used to generate crosslinking sites on the surface of ammonium perchlorate in solid interceptor propellants to improve elongation of the propellant.